1. Field of the Invention
The present invention relates to a torque limiter which requires no parts replacement or oil resupply for its restoration.
2. Description of the Prior Art
Conventionally, in a torque limiter, for example, as shown in FIG. 9, the cylindrical inner circumferential surface of a cylinder member 2 is fitted to the cylindrical outer circumferential surface of a shaft member 1. Oil is supplied to a hydraulic slit 2a of the cylinder member 2, which is sealed by a shear tube 3. An engaging member 4 engageable with an end of the shear tube 3 is secured to the shaft member 1. (See Japanese Patent Publication No. 63-30527.)
The oil under pressure within the hydraulic slit 2a causes the cylindrical inner circumferential surface of the cylinder member 2 to contract so that the cylindrical inner circumferential surface is urged against the cylindrical outer circumferential surface of the shaft member 1. This makes the shaft member 1 and the cylinder member 2 frictionally coupled, allowing a torque to be transmitted therebetween. When a load above a specified value is applied to the shaft member 1 or the cylinder member 2, the shaft member 1 slips relative to the cylindrical inner circumferential surface of the cylinder member 2 such that the shaft member 1 and the cylinder member 2 are rotated relative to one another, and the end of the shear tube 3 is cut off by the engaging member 4, causing the oil within the hydraulic slit 2a to be discharged. As a result, the shaft member 1 and the cylinder member 2 are uncoupled, the torque no longer being transmitted therebetween.
However, in the above conventional torque limiter, not only is the shear tube 3 cut off but the oil within the hydraulic slit 2a is discharged. Therefore, the shear tube 3 must be replaced and oil equivalent to that discharged must be resupplied to the hydraulic slit 2a at the time of restoration.